arXiv:2212.03610 · Physical Review Research

Self-bound clusters of one-dimensional fermionic mixtures

M. C. Gordillo

Published Nov 13, 2023• 2 citations

Abstract

Diffusion Monte Carlo calculations on the possibility of having self-bound one-dimensional droplets of SU(6) $\ifmmode\times\else\texttimes\fi{}$ SU(2) ultracold fermionic mixtures are presented. We found that, even though arrangements with attractive interactions with only two spin types are not self-bound, mixtures with at least three kinds of fermions form stable small drops. However, that stabilization decreases for very tight confinements, where a universal behavior is found for Fermi-Fermi and Fermi-Boson clusters including attractive and repulsive interactions.

DOI: 10.1103/physrevresearch.5.043144

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arXiv:2212.03610 · Physical Review Research

Self-bound clusters of one-dimensional fermionic mixtures

M. C. Gordillo

Published Nov 13, 2023• 2 citations

arXiv HTML PDF

Abstract

Diffusion Monte Carlo calculations on the possibility of having self-bound one-dimensional droplets of SU(6)

\ifmmode\times\else\texttimes\fi{}

SU(2) ultracold fermionic mixtures are presented. We found that, even though arrangements with attractive interactions with only two spin types are not self-bound, mixtures with at least three kinds of fermions form stable small drops. However, that stabilization decreases for very tight confinements, where a universal behavior is found for Fermi-Fermi and Fermi-Boson clusters including attractive and repulsive interactions.

DOI: 10.1103/physrevresearch.5.043144

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Unbalanced droplets of one-dimensional mixtures of fermions

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By means of a diffusion Monte Carlo technique, we study one-dimensional unbalanced mixtures of fermionic ytterbium atoms ( $^{173}\mathrm{Yb}$ and $^{171}\mathrm{Yb}$ ). This means clusters in which the total number of $^{173}\mathrm{Yb}$ particles is different from the sum of all the atoms belonging to the $^{171}\mathrm{Yb}$ isotope. Our aim will be to check the possibility of having self-bound arrangements beyond the balanced compositions reported in previous literature rather than exploring all the situations in which that could be possible. In that vein, we focused mainly on mixtures in which the atoms belonging to one isotope are spin polarized, while the spins of the particles in the other isotope are evenly distributed in two sets. What we found was that, even though self-bound droplets are possible for different compositions, the most stable ones are clusters with a slight excess of attractively interacting $^{171}\mathrm{Yb}$ particles with different spins with respect to the number of spin-polarized $^{173}\mathrm{Yb}$ atoms. Clusters in which the number of repulsively interacting unequal-spin $^{173}\mathrm{Yb}$ atoms are in excess with respect to the spin-polarized $^{171}\mathrm{Yb}$ particles have a very narrow stability range.By means of a diffusion Monte Carlo technique, we study one-dimensional unbalanced mixtures of fermionic ytterbium atoms ($^{173}\mathrm{Yb}$ and $^{171}\mathrm{Yb}$). This means clusters in which the total number of $^{173}\mathrm{Yb}$ particles is different from the sum of all the atoms belonging to the $^{171}\mathrm{Yb}$ isotope. Our aim will be to check the possibility of having self-bound arrangements beyond the balanced compositions reported in previous literature rather than exploring all the situations in which that could be possible. In that vein, we focused mainly on mixtures in which the atoms belonging to one isotope are spin polarized, while the spins of the particles in the other isotope are evenly distributed in two sets. What we found was that, even though self-bound droplets are possible for different compositions, the most stable ones are clusters with a slight excess of attractively interacting $^{171}\mathrm{Yb}$ particles with different spins with respect to the number of spin-polarized $^{173}\mathrm{Yb}$ atoms. Clusters in which the number of repulsively interacting unequal-spin $^{173}\mathrm{Yb}$ atoms are in excess with respect to the spin-polarized $^{171}\mathrm{Yb}$ particles have a very narrow stability range.

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arXiv:2004.05737Chinese Physics LettersJul 1, 202017 citations

Diffusion Monte Carlo calculations on the possibility of having self-bound one-dimensional droplets of SU(6)

\ifmmode\times\else\texttimes\fi{}

By means of a diffusion Monte Carlo technique, we study one-dimensional unbalanced mixtures of fermionic ytterbium atoms (

^{173}\mathrm{Yb}

and

^{171}\mathrm{Yb}

). This means clusters in which the total number of

^{173}\mathrm{Yb}

particles is different from the sum of all the atoms belonging to the

^{171}\mathrm{Yb}

isotope. Our aim will be to check the possibility of having self-bound arrangements beyond the balanced compositions reported in previous literature rather than exploring all the situations in which that could be possible. In that vein, we focused mainly on mixtures in which the atoms belonging to one isotope are spin polarized, while the spins of the particles in the other isotope are evenly distributed in two sets. What we found was that, even though self-bound droplets are possible for different compositions, the most stable ones are clusters with a slight excess of attractively interacting

^{171}\mathrm{Yb}

particles with different spins with respect to the number of spin-polarized

^{173}\mathrm{Yb}

atoms. Clusters in which the number of repulsively interacting unequal-spin

^{173}\mathrm{Yb}

atoms are in excess with respect to the spin-polarized

^{171}\mathrm{Yb}

particles have a very narrow stability range.

We present diffusion Monte Carlo calculations on the behavior of a mixture of

^{173}\mathrm{Yb}

and

^{171}\mathrm{Yb}

fermionic isotopes in a one-dimensional environment. The interaction parameters between species were modeled by $\ensuremath{\delta}$ potentials, whose strengths were taken from their experimental scattering lengths and varied by changing the transversal confinement. This implies a repulsive interaction for the $^{173}\mathrm{Yb}\ensuremath{-}^{173}\mathrm{Yb}$ pair, a strong attractive one for the $^{173}\mathrm{Yb}\ensuremath{-}^{171}\mathrm{Yb}$ set, and a weak attraction between $^{171}\mathrm{Yb}\ensuremath{-}^{171}\mathrm{Yb}$ atoms. Those arrangements were described by a corrected geminal multiplied by the appropriate set of Jastrow functions. We found that, for the same number of strong attractive pairs, the width of the cluster decreases when the number of fermionic species increases, the narrower cluster being the one that includes a mixture of six

^{173}\mathrm{Yb}

species and two

^{171}\mathrm{Yb}

spin types.

^{41}

\,

^{40}

^{87}

\,

^{40}

K, and

^{133}

\,

^{6}

Li as a function of the ratio of Bose-Fermi to Bose-Bose scattering length. The stability analysis is supported by a numerical simulations of droplet formation dynamics starting with a trapped system which is subsequently released from the trap. Our results indicate that Bose-Fermi droplets can be realized experimentally.